When the COVID-19 pandemic reached the United States in early 2020 federal health officials said Coronavirus didn’t really affect children. But doctors in the U.S. and other countries have since seen hundreds of cases of a new illness related to COVID-19: Multisystem Inflammatory Syndrome in Children (MIS-C). Some kids and teenagers have died.

“On April 26, 2020, clinicians in the United Kingdom (UK) recognized increased reports of previously healthy children presenting with a severe inflammatory syndrome with Kawasaki disease-like features. The cases occurred in children testing positive for current or recent infection by SARS-CoV-2, the novel coronavirus that causes COVID-19,” according to the CDC’s website. “CDC is still learning about MIS-C and how it affects children, so we don’t know why some children have gotten sick with MIS-C and others have not. We also do not know if children with certain health conditions are more likely to get MIS-C.”